import struct
from xml.etree import ElementTree

import pytest

from app import config


@pytest.fixture(params=["svg", "png"])
def image_url(request):
    return f"/placeholder.{request.param}"


def test_health(client):
    response = client.get("/healthz")

    assert response.status_code == 200
    assert response.json == {"status": "ok"}
    assert "Cache-Control" not in response.headers


@pytest.mark.parametrize("custom_dimensions", [False, True])
def test_image_output(client, image_url, custom_dimensions):
    parameters = {"width": 321, "height": 123, "font_size": 17} if custom_dimensions else {}
    width = parameters.get("width", config.DEFAULT_IMAGE_WIDTH)
    height = parameters.get("height", config.DEFAULT_IMAGE_HEIGHT)
    font_size = parameters.get("font_size", config.DEFAULT_FONT_SIZE)

    response = client.get(image_url, query_string=parameters)

    assert response.status_code == 200
    if image_url.endswith(".svg"):
        assert response.mimetype == "image/svg+xml"
        root = ElementTree.fromstring(response.data)  # noqa: S314 - trusted SVG generated by the app
        assert root.tag == "{http://www.w3.org/2000/svg}svg"
        assert root.attrib["width"] == str(width)
        assert root.attrib["height"] == str(height)
        text = root.find("{http://www.w3.org/2000/svg}text")
        assert text is not None
        assert text.attrib["font-size"] == str(font_size)
        assert text.text == f"{width} × {height}"
    else:
        assert response.mimetype == "image/png"
        assert response.data[:8] == b"\x89PNG\r\n\x1a\n"
        assert response.data[12:16] == b"IHDR"
        # IHDR starts with width and height as big-endian unsigned 32-bit integers.
        assert struct.unpack(">II", response.data[16:24]) == (width, height)


@pytest.mark.parametrize(
    ("parameter", "maximum"),
    [
        ("width", config.MAX_IMAGE_WIDTH),
        ("height", config.MAX_IMAGE_HEIGHT),
        ("font_size", config.MAX_FONT_SIZE),
    ],
)
@pytest.mark.parametrize("boundary", ["below", "minimum", "maximum", "above"])
def test_parameter_bounds(client, image_url, parameter, maximum, boundary):
    value = {"below": 0, "minimum": 1, "maximum": maximum, "above": maximum + 1}[boundary]
    # Vary one bound at a time, keeping the other dimensions small for cheap renders.
    parameters = {"width": 10, "height": 10, "font_size": 1, parameter: value}

    response = client.get(image_url, query_string=parameters)

    if boundary in {"minimum", "maximum"}:
        assert response.status_code == 200
    else:
        assert response.status_code == 400
        assert response.json == {
            "status": "error",
            "message": f"{parameter} outside of allowable range",
        }
        assert "Cache-Control" not in response.headers


@pytest.mark.parametrize("timeout", [config.CACHE_DEFAULT_TIMEOUT, 120])
def test_image_cache_control(app, client, image_url, timeout):
    # An override catches headers that hard-code the default timeout.
    app.config["CACHE_DEFAULT_TIMEOUT"] = timeout

    response = client.get(image_url)

    assert response.status_code == 200
    assert response.cache_control.public
    assert response.cache_control.max_age == timeout
    assert not response.cache_control.no_cache
    assert not response.cache_control.no_store


def test_cached_image_survives_render_limit(client, image_url, monkeypatch):
    limit_name = "SVG_RENDER_LIMIT" if image_url.endswith(".svg") else "PNG_RENDER_LIMIT"
    # Exhaust the render quota with one request; the request quota remains available.
    monkeypatch.setattr(config, limit_name, "1/minute")

    first = client.get(image_url, query_string={"width": 10, "height": 10})
    assert first.status_code == 200

    # A new size needs a render, but the original size should still come from cache.
    uncached = client.get(image_url, query_string={"width": 11, "height": 10})
    assert uncached.status_code == 429
    assert "Cache-Control" not in uncached.headers

    cached = client.get(image_url, query_string={"width": 10, "height": 10})
    assert cached.status_code == 200
    assert cached.data == first.data